Old stereo records claim "Do not play with a mono cartridge..."

What I want to know is, what exactly is supposed to happen if you do, and what exactly will the sonic difference be when played again with a stereo cartridge? None of this was ever explained, other than "mono cartridges lack vertical compliance required to track stereo grooves," but I want to know what to listen for as far as damage to the recording when played in stereo after-the-fact. Nobody has ever bothered to explain this. I have played junk stereo LPs (Jerry Vale, John Davidson, and The Stradivari Strings come to mind) with a mono cartridge and have heard no worse sound when played again in stereo. I would think this would be an important issue for collectors buying used stereo LPs on eBay, GEMM, and other sites offering used vinyl, as someone may be selling a stereo copy of an LP that for the life of it was always played with a mono cartridge. I know of a Ronnie Aldrich fan who had an Emud mono console, bought all of Ronnie's London Phase 4 stereo albums, but since no mono copies were available commercially, the guy had no choice but to play the LPs on his mono console. So what's the deal here? If such records are bought and played in stereo, what's to be expected of the sound? Someone must know the answer to this.

 

The stereo police will come to your house and issue you a citation for not playing the stereo record with a stereo cartridge.

The mattress police follow a similar beat...

 

One thing to keep in mind - modern mono cartridges do have vertical compliance.

 

I was referring to 50s and early 60s vintage cartridges, such as the GE "Triple Play" RPX series and the GE VRII, as well as some old turnover / flip under Sonotones, Astatics, E-Vs, and Ronettes. These did not come with .7 mil styli, as stereo records were either not yet in production or were in their infancy. I know all about the warnings and the theory behind WHY playing stereo discs with these cartridges allegedly isn't a good idea, but what are the repercussions of doing so? I've never been able to detect any adverse effect after playing a stereo disc with a non-compliant mono cartridge. The stereo separation is still there, and there's no detectable increase in surface noise, so what's the big deal? Everyone knows that you shouldn't do it, but nobody seems to know what the expected result is if you did.

I know that with classroom record players, Astatic and E-V replaced the original 81T and 81 with 89T and 89. The replacements were stereo compatible, whereas the predecessors were not. When I was in high school, the players still had the older 81T cartridges in them, but they didn't appear to have damaged any of either my or my classmates' stereo records. I'm looking for someone to tell me they played a stereo record with a mono cartridge and there was an audible difference after the fact and exactly what that difference was. Otherwise, I will conclude that the whole idea was jive, concocted by the record industry to get people to buy duplicate copies of the same LPs to play on two different players types of players, which is what I suspect it is. The difference between a 1.0 mil conical stylus and a .7 mil conical stylus is only .3 mil, a miniscule difference that as far as the two types of record grooves go shouldn't matter. That said, if the cartridge can't move up and down with the vertical modulation, what is the auditory result after-the-fact? Has anyone ever heard an audible or even measurable difference after playing a stereo disc with a hi-fi mono cartridge not intended for it? That is the question for which I'm seeking an answer.

 

It was mainly CYA. Most cartridges really do have some vertical compliance, even the old mono ones and so, would not necessarily damage stereo grooves.

It's still a crap shoot, however. I wouldn't want to risk my stereo records with one of those old cartridges.

Doug

 

I have for years been under the impression that the needle on a mono cartridge is wider than that of a stereo cartridge. Not sure where that comes from though.

 

It's 1 mil (mono) and .7 mil (stereo) for the original conical styli. The difference was made because it was deemed that a .7 mil stylus would be a better fit in the stereo groove what with the back-and-forth, side-to-side, and movements at all angles in between. However, it will not harm a stereo record to use a 1 mil stylus or harm a mono record to use a .7 mil stylus. The styli just ride at slightly different heights in the groove.

Doug

 

Will your stereo records catch mono?

 

Accelerated groove wear. The early stereo records had the bass cut in stereo, this would make the stylus cut into the highly modulated passages. Bass was summed to mono starting around 1967 to deal with the problem.

 

Stylus size aside, what about the lack of vertical movement that characterizes a mono cartridge? According to all the warnings on the backs of LP jackets such as Capitol stereo releases, "This stereo record should be played only with a stereo needle and cartridge to avoid damage." I'm trying to gauge what exactly this damage might be, and exactly how playing such a record with a mono cartridge without vertical compliance affects the stereo reproduction after-the-fact. My ears tell me that it does not, yet folks here claim that one should not play a post-1967 MONO record with such a cartridge because those were cut using stereo cutters. I have never encountered ANY difference in sound after playing either a true stereo or post-1967 mono release with a non-vertically compliant mono cartridge. This leads me to believe that the claims made by record manufacturers between 1958 and 1967 is pure B.S., and that the claim that "Columbia stereo records can be played on modern mono players with excellent results" is just more of the same. As I posted above, I have played early 60s junk LPs on a 1955 Voice of Music record changer with a GE "Triple Play" RPX series cartridge, then played the same record on a Technics SL-1200 MkII with a Shure M91ED and have heard no degradation in sound. The stereo separation was the same as before, surface noise wasn't apparently increased, and the overall fidelity was the same as before. This cartridge's recommended VTF is 8 grams, and since I use the same cartridge to play both mono LPs and 45s (with a 1.0 mil stylus) and 78 rpm records (with a 3.0 mil stylus, of course), the tracking force is set at 8 grams. Still, I can detect no audible damage to a stereo LP after playing it with the GE cartridge. Surely SOMEONE on this forum has some experience with this issue and can tell me what to listen for after tracking a stereo disc with such an old mono cartridge and stylus!

 

Not that I can prove! I'm not suggesting that I would play my MFSL copy of "Dark Side of the Moon" on my 1955 mono changer with it's old GE RPX cartridge, but I'd like someone to tell me what I should be listening for if I DID. Everyone here knows that I shouldn't, including myself, but surely someone here HAS played a stereo LP on an old mono player just to see what would happen, and I'm trying to get them to tell me the result and what I should notice for audible damage after doing so.

 

I can understand that, as mono cartridges tend to track heavier than most stereo cartridges, yet a 1960 portable stereo from The Voice of Music came with an Astatic 80TS stereo crystal cartridge with a recommended VTF of 8 grams. Now, my guess is that a mono cartridge with a 1.0 mil stylus would wear a stereo record less than a stereo cartridge with a .7 mil stylus at the same VTF, so what's the point? The lateral modulation on a stereo disc is a summed signal anyway, so regardless of whether bass was centered or off to 0ne side, a mono cartridge is only going to reproduce the summed signal anyway. The vertical modulation is a difference signal, but since a mono cartridge ignores it, unless something common to both channels is out-of-phase (early Capitol stereo LPs were notorious for this), the mono cartridge will reproduce a stereo LP using only the L+R information found in the lateral groove modulation.